The SEGUE study examines safety, tolerability, effectiveness, and treatment optimization in participants with narcolepsy transitioning from sodium oxybate (SXB) to lower-sodium oxybate (LXB; Xywav^®).

LXB contains 92% less sodium than SXB and is approved for treating cataplexy or excessive daytime sleepiness (EDS) in patients with narcolepsy (≥7 years of age).

Eligible participants in this ongoing, multicenter, open-label study (NCT04794491) are adults with narcolepsy (type 1 or 2) on an SXB stable dose (maximum 9 g/night; no single dose >6 g) and regimen (once, twice, or thrice nightly). After 2 weeks on SXB (baseline period), participants switch to the same LXB dose/regimen (intervention period; 6 weeks). If needed, LXB dose/regimen is titrated to optimize efficacy/tolerability. Assessments include the Patient Global Impression of Change (PGIc), forced preference questionnaire (FPQ), and ease of switching medication scale (EOSMS; all collected at end of treatment/early discontinuation). An interim analysis (first 24 completers) is reported.

Most participants were White (92%); 54% were female; mean (SD) age was 45.5 (16.20) years. Starting and ending (end of treatment/early discontinuation) median total nightly doses of LXB were both 9.0 g. Most participants took LXB twice nightly (88%). Twenty-two participants completed the transition period; mean (SD) time to optimized dose was 1.4 (1.56) days, and median (range) number of dose/regimen changes was 0.0 (0, 1). At end of treatment/early discontinuation, most reported improvement (very much/much/minimal; 57%) or no change (43%) in narcolepsy symptoms on the PGIc, preferred LXB over SXB on the FPQ (86%), and reported the transition was easy (easy/extremely easy/not difficult at all) on the EOSMS (91%). Most treatment-emergent adverse events reported were mild to moderate.

Participants switched from SXB to LXB with minimal modifications of dose/regimen and reported the transition was easy. Efficacy of oxybate treatment was maintained or improved, and most participants preferred LXB over SXB.